WASHINGTON – In an effort to prevent whiplash, federal regulators will require vehicle headrests to be higher and closer to the head by 2008 under a safety standard released yesterday.

The new rule won't require headrests in the back seat. Some safety advocates and Honda Motor Co. wanted back seat headrests to be mandated, but other automakers and seat suppliers were opposed.

The National Highway Traffic Safety Administration said the cost of requiring back seat head restraints was too high considering the few whiplash injuries in back seats. NHTSA Administrator Dr. Jeffrey Runge said drivers also have complained about visibility problems when they have back seat head restraints.

"When we did our analysis, 90 percent of the time there's nobody in the back seat of vehicles and the other 10 percent of the time that there are, it's kids," Runge said. "But this doesn't stop manufacturers from putting it in their back seats. Based on their user profile, if it's a safe thing to do, they'll do that."

NHTSA established rules for automakers who install back seat headrests voluntarily.

The agency estimates there are 270,000 whiplash injuries each year. NHTSA believes the new rule will prevent 16,831 injuries and save more than $100 million in medical bills and other costs.

NHTSA said it will cost $4.51 per vehicle to meet the front seat requirement. For automakers that are already installing back seat headrests, it would cost $1.13 per car to meet the new rules for them. The total cost to the industry will be $84.2 million, NHTSA said.

The Alliance of Automobile Manufacturers, a Washington group that represents 10 automakers, was generally supportive of the rule. The group had petitioned NHTSA to update its standards because it was concerned about visibility, spokesman Eron Shosteck said. Automakers must comply with the new rules by Sept. 1, 2008.

Gerald Donaldson, senior research director for the nonprofit Advocates for Highway and Auto Safety, said he was dismayed by the new rule, complaining that NHTSA had weakened or discarded many of its own proposals.

For example, NHTSA wanted to require nonremovable head restraints, but automakers said that would make it more difficult to fold the seats down. NHTSA agreed not to require them.

NHTSA also wanted to allow less room between an occupant's head and the headrest, but agreed to allow five more millimeters of space because automakers were concerned that consumers would be uncomfortable.